A method of controlling a washing machine includes: sensing a laundry amount accommodated in a drum; performing water supply into the drum according to the sensed laundry amount; rotating a pump motor at a certain initial rotation speed and transferring washing water discharged from the drum to at least one nozzle for spraying water into the drum; sensing a water level in the drum; performing a re-supply of water at least once until the sensed water level reaches a set water level; and increasing the rotation speed of the pump motor whenever the re-supply of water is performed, so that as the rotation speed of the pump motor is increased, the reaching range of the water stream sprayed through the nozzle gradually expands from the lower side of the circumferential surface of the drum to the rear surface of the drum.